EP1247825B1 - Latent cross-linkable aqueous dispersions comprising a polyurethane - Google Patents

Description

1. I) eine disperse Phase (P.I), enthaltend
   • Ia) ein Polyurethan (Ia), das neben hydrophilen Gruppen, die die Wasserdispergierbarkeit bewirken, Carbodiimid-Gruppen trägt und im wesentlichen keine Carboxylgruppen trägt
     oder
   • Ib) eine physikalische Mischung aus
     • Ibi) einem Polyurethan (Ibi), das hydrophile Gruppen, die die Wasserdispergierbarkeit bewirken, trägt und im wesentlichen keine Carbodiimid oder Carboxylgruppen trägt, und
     • Ibii) einem Carbodiimid (Ibii), das im wesentlichen keine hydrophilen Gruppen, die die Wasserdispergierbarkeit bewirken, trägt,
   und
2. II) eine disperse Phase (P.II), enthaltend ein sonstiges Polymer (II), das im wesentlichen keine Carbodiimid-Gruppen trägt und im wesentlichen abgeleitet ist von
   • II.1) 30 bis 99,98 Gew.-% Hauptmonomere ausgewählt aus C₁bis C₂₀-Alkyl(meth)acrylaten, Vinylestern von bis zu 20 C-Atome enthaltenden Carbonsäuren, Vinylaromaten mit bis zu 20 C-Atomen, ethylenisch ungesättigten Nitrilen, Vinylhalogeniden und aliphatischen Kohlenwasserstoffen mit 2 bis 8 C-Atomen und 1 oder 2 Doppelbindungen,
   • II.2) 0,01 bis 20 Gew.-% einer Carbonsäure mit einer olefinischen Doppelbindung und
   • II.3) 0,01 bis 10 Gew.-% eines von den Monomeren II.1 und II.2 verschiedenen Monomeren, ausgewählt aus der Gruppe bestehend aus N-Methylol(meth)acrylamid (AMOL), (MAMOL), Acetoacetoxy-ethyl-(meth)acrylat; Diaceton(meth)acrylamid; Gycidyl(meth)acrylat; Ureido-(meth)acrylat; (Meth)acrylsäureanhydrid,
   • II.4) ggf. von (II.1), (II.2) und (II.3) verschiedenen radikalisch polymerisierbaren Monomeren.

Latent crosslinking aqueous polyurethane dispersions containing

1. I) a disperse phase (PI) containing
   • Ia) a polyurethane (Ia), in addition to hydrophilic groups which cause the water dispersibility carrying carbodiimide groups and carries substantially no carboxyl groups
     or
   • Ib) a physical mixture
     • Ibi) a polyurethane (Ibi) which carries hydrophilic groups, which cause the water dispersibility, and carries substantially no carbodiimide or carboxyl groups, and
     • Ibii) a carbodiimide (Ibii), which carries substantially no hydrophilic groups, which cause the water dispersibility,
   and
2. II) a disperse phase (P.II) containing another polymer (II) which carries substantially no carbodiimide groups and is substantially derived from
   • II.1) from 30 to 99.98% by weight of main monomers selected from C ₁ to C ₂₀ -alkyl (meth) acrylates, vinyl esters of carboxylic acids containing up to 20 C atoms, vinylaromatics having up to 20 C atoms, ethylenically unsaturated Nitriles, vinyl halides and aliphatic hydrocarbons having 2 to 8 C atoms and 1 or 2 double bonds,
   • II.2) 0.01 to 20 wt .-% of a carboxylic acid having an olefinic double bond and
   • II.3) 0.01 to 10 wt .-% of a monomer other than the monomers II.1 and II.2, selected from the Group consisting of N-methylol (meth) acrylamide (AMOL), (MAMOL), acetoacetoxyethyl (meth) acrylate; Diacetone (meth) acrylamide; Glycidyl (meth) acrylate; Ureido (meth) acrylate; (Meth) acrylic anhydride,
   • II.4) optionally of (II.1), (II.2) and (II.3) different radically polymerizable monomers.

Furthermore, the invention relates to the use of the aqueous dispersions according to the invention as impregnating agent, coating agent or adhesive as well as the impregnated, coated or bonded articles produced using these dispersions.

Aqueous dispersions containing a polyurethane in dispersed form are well known. In order to have coatings which are produced from the polyurethane having particularly good mechanical properties, these dispersions are admixed with a crosslinking component. It is particularly desirable that the crosslinking agent effects the molecular weight buildup of the polyurethane only when the polyurethane dispersion has already been converted into a film after application to the workpiece to be coated. Under these circumstances, films are obtained which have a particularly high cohesion, since then the polymer molecules of one dispersion particle can also be linked to the polymer molecules of another adjacent dispersion particle via a covalent bond.

A particularly good cohesion of the films is required, for example, in the adhesive area, especially when the adhesive bond is subjected to mechanical stress under the action of heat.

To obtain adhesive bonds that still have sufficient strength under these conditions, z. B. in EP-A-206059 recommended to add a water-emulsifiable polyisocyanate to the dispersions shortly before their processing as an adhesive crosslinker.

The disadvantage of these two-component systems, however, is that the pot life, ie the period in which these systems can be processed after their mixing, is narrowly limited. Since the two-component system can not be stored for an extended period of time and the processor has to produce a certain amount of adhesive, which he can process within one working cycle, the workload for the processor of the adhesives in two-component systems is increased over one-component systems ,

US 4977219 and 5117059 disclose mixtures of an aqueous dispersion of a carbodiimide and an aqueous dispersion of an emulsion polymer having carboxylate groups, the first-mentioned dispersion being stabilized with the aid of conventional surface-active substances.

US 5574083 relates to a mixture of an aqueous dispersion of carbodiimides, wherein the dispersion is stabilized by hydrophilic polyalkylene oxide radicals which carry the carbodiimides. These dispersions are blended with aqueous dispersions of an emulsion polymer having carboxylate groups.

EP-A-792908 discloses mixtures of an aqueous dispersion of a carboxyl group-bearing polyurethane and an aqueous dispersion of a carbodiimide, the dispersion being stabilized with the aid of conventional surface-active substances.

EP-A-198343 relates to carbodiimide group-containing polyurethanes having hydrophilic groups which enable water dispersibility. According to this teaching, the carboxyl-containing polymer dispersions are added and cause a crosslinking effect in the polymers.

According to the teaching of the abovementioned documents, the carbodiimides cause an increase in molecular weight of the carboxyl-containing polymers with which they are blended. However, the strength of bonds made with these dispersions, especially in the heat leaves much to be desired. Furthermore, the pot life of such mixtures is limited.

DE-A-19733044 relates to aqueous dispersions of a polyurethane bearing carbodiimide groups.

From DE-A-19828251 aqueous dispersions are described which contain 2 different types of dispersion particles, of which the first contain polyurethanes with carbodiimide groups or mixtures of polyurethanes and carbodiimides and the second other polymers with carboxyl groups.

The dispersions prepared according to the teaching of the two last-mentioned publications already meet the adhesive-technical requirement profile. However, workpieces pretreated with these dispersions have too low blocking resistance. By blocking resistance we mean the property that workpieces which have been wetted with the dispersion, after drying when applied Do not stick to each other or to other objects with little pressure.

Thus, the prepared workpieces, when stacked, and the pressure applied to the adhesive surfaces pressure is less than 1 kg / cm ² , even after prolonged storage still be powerless separable. Only when applying a pressure of about 0.5 N / mm ² , as it is typically used in bonding the pretreated workpieces, a strongest possible adhesive bond should arise.

As a result, the organization of work in the production of the bonded objects is significantly simplified. Only with substantially block-free adhesive-coated workpieces, it is practically possible to separate the processing step of the adhesive coating of the actual bonding of the adhesive-coated workpieces spatially or temporally, as this requires efficient storage and transport.

The object of the present invention was therefore to provide a further one-component polyurethane dispersion which does not have the disadvantages of the prior art. In particular, it should have good storage stability and be further improved with respect to the blocking resistance of the workpieces prepared therewith.

Accordingly, the aqueous dispersions defined above were found.

The disperse phase P.I generally contains 0.01 to 1, preferably 0.1 to 0.5, particularly preferably 0.15 to 0.4 mol of carbodiimide groups per kg of monomers used for the synthesis of the polyurethanes Ia or Ibi and Ibii.

Suitable polyurethanes (Ia) are described, for example, in EP-A-792908.

In principle, suitable polyurethanes (Ia) are all hydrophilic polyurethanes, in the construction of which monomers with carbodiimide structural units are also used. The carbodiimide structural units are preferably introduced into the polyurethane (Ia) via polyisocyanates (Ia1.1) containing one or more of the carbodiimide structural units. Such polyisocyanates (Ia1.1) preferably obey the general formula Ia1.1.1

OCN- (R ^c -N = C =N) _n -R ^c -NCO (Ia1.1.1)

in the R ^c for a divalent, optionally urea, urethane, ester, and / or ether groups containing hydrocarbon radical, such as by removal of the isocyanate groups from a simple organic isocyanate or a urethane group and optionally ether or ester group-containing prepolymer, the terminal Isocyanate groups, is obtained, wherein in the presence of multiple radicals R ¹ in the same molecule at the same time may also be different, corresponding to said definition radicals R ¹ , and
n is an integer or (in statistical average) number from 1 to 20, preferably from 2 to 10.

mit

• R^a: eine Gruppe der Formel Ia1.1.2.1
  
• R^b: eine Gruppe der Formel Ia1.1.2.2
  
  und
• m: eine Zahl von 1 bis 20

The carbodiimide structural units are particularly preferably introduced into the polyurethane (Ia) via polyisocyanates of the general formula Ia1.1.2

With

• R ^a : a group of formula Ia1.1.2.1
  
• R ^b : a group of formula Ia1.1.2.2
  
  and
• m: a number from 1 to 20

• Ia1) Diisocyanaten, die
  • Ia1.1) Carbodiimid-Struktureinheiten enthalten und
    gegebenenfalls solchen,
  • Ia1.2) die frei sind von Carbodiimid-Struktureinheiten,
• Ia2) Diolen, von denen
  • Ia2.1) 10 bis 100 mol-%, bezogen auf die Gesamtmenge der Diole (b), ein Molekulargewicht von 500 bis 5000 aufweisen, und
  • Ia2.2) 0 bis 90 mol-%, bezogen auf die Gesamtmenge der Diole (Ia2), ein Molekulargewicht von 60 bis 500 g/mol aufweisen,
• Ia3) von den Monomeren (Ia1) und (Ia2) verschiedene Monomere mit wenigstens einer Isocyanatgruppe oder wenigstens einer gegenüber Isocyanatgruppen reaktiven Gruppe, die darüber hinaus wenigstens eine hydrophile Gruppe oder eine potentiell hydrophile Gruppe tragen, wodurch die Wasserdispergierbarkeit der Polyurethane bewirkt wird,
• Ia4) gegebenenfalls weiteren von den Monomeren (Ia1) bis (Ia3) verschiedenen mehrwertigen Verbindungen mit reaktiven Gruppen, bei denen es sich um alkoholische Hydroxylgruppen, primäre oder sekundäre Aminogruppen oder Isocyanatgruppen handelt und
• Ia5) gegebenenfalls von den Monomeren (Ia1) bis (Ia4) verschiedenen einwertigen Verbindungen mit einer reaktiven Gruppe, bei der es sich um eine alkoholische Hydroxylgruppe, eine primäre oder sekundäre Aminogruppe oder eine Isocyanatgruppe handelt.

In general, the polyurethanes (Ia) are otherwise composed of

• Ia1) diisocyanates, the
  • Ia1.1) contain carbodiimide structural units and
    where appropriate,
  • Ia1.2) which are free of carbodiimide structural units,
• Ia2) Diols, of which
  • Ia2.1) 10 to 100 mol%, based on the total amount of diols (b), have a molecular weight of 500 to 5000, and
  • Ia2.2) 0 to 90 mol%, based on the total amount of diols (Ia2), have a molecular weight of 60 to 500 g / mol,
• Ia3) monomers other than the monomers (Ia1) and (Ia2) having at least one isocyanate group or at least one isocyanate group-reactive group which moreover bear at least one hydrophilic group or a potentially hydrophilic group, thereby causing the water dispersibility of the polyurethanes;
• Ia4) optionally other than the monomers (Ia1) to (Ia3) different polyvalent compounds having reactive groups which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups, and
• Ia5) optionally of the monomers (Ia1) to (Ia4) different monovalent compounds having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.

Suitable diisocyanatocarbodiimides (Ia1.1) are, in particular, those of the general formula Ia1.1.1 or Ia1.1.2.

The radicals R ^c in formula Ia1.1.1 are preferably derived by abstraction of the isocyanate groups from monomers (Ia1.2), which are the diisocyanates which are customarily used in polyurethane chemistry.

To be mentioned in particular as monomers (Ia1.2) diisocyanates X (NCO) ₂ , wherein X is an aliphatic hydrocarbon radical having 4 to 12 carbon atoms, a cycloaliphatic or aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms , Examples of such diisocyanates are tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,2-bis (4-isocyanatocyclohexyl) -propane, trimethylhexane diisocyanate , 1,4-diisocyanatobenzene, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanato-diphenylmethane, 2,4'-diisocyanato-diphenylmethane, p-xylylene diisocyanate, tetramethylxylylene diisocyanate (TMXDI), the isomers of bis - (4-isocyanatocyclohexyl) methane (HMDI) as the trans / trans, the cis / cis and the cis / trans isomers and mixtures consisting of these compounds.

The radicals R ^c , which are derived by abstraction of the isocyanate groups from a urethane group, optionally ether or ester groups and terminal isocyanate groups having prepolymer, are preferably those from the diols (Ia2) and the diisocyanates (Ia1.2 ) are constructed.

The preparation of the monomers (Ia1.1) is known per se and is e.g. in US 2,840,589, 2,941,966 and EP-A-628,541 and P.W. Campbell and K.C. Smeltz in Journal of Organic Chemistry, 28, 2069 (1963). Particularly gentle and free of by-products, diisocyanatocarbodiimides can also be prepared by heterogeneous catalysis according to German Offenlegungsschriften 2,504,400 and 2,552,350. The carbodiimidization of diisocyanates in the presence of very small amounts of phospholine oxide with subsequent blocking of the catalyst with acid chlorides is described in DE-OS 2,653,120.

In general, in addition to the preparation of the diisocyanates (Ia1.1), the diisocyanates (Ia1.2) are also used directly for the synthesis of the polyurethanes which are present in polyurethane dispersions according to the invention, since more isocyanate is frequently required to form the polyurethanes than is required for the introduction of the polyurethanes Carbodiimide groups is required.

For the construction of the polyurethanes can be used as compounds (Ia1.2) except the aforementioned also isocyanates, which in addition to the free isocyanate groups further blocked isocyanate groups, e.g. Wear uretdione groups.

With regard to good film formation and elasticity, particularly suitable diols (Ia2) are relatively high molecular weight diols (Ia2.1) which have a molecular weight of about 500 to 5000, preferably about 1000 to 3000 g / mol.

The diols (Ia2.1) are, in particular, polyesterpolyols which are known, for example, from Ullmanns Encyklopadie der technischen Chemie, 4th edition, volume 19, pages 62 to 65. Preference is given to using polyesterpolyols which are obtained by reacting dihydric alcohols with dibasic carboxylic acids. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof to prepare the polyesterpolyols. The polycarboxylic acids may be aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic and may optionally be substituted, for example by halogen atoms, and / or unsaturated. Examples of these are: suberic acid, azelaic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimer fatty acids. Preference is given to dicarboxylic acids of the general formula HOOC (CH ₂ ) _y -COOH, where y is a number from 1 to 20, preferably an even number from 2 to 20, for example succinic acid, adipic acid, sebacic acid and dodecanedicarboxylic acid.

Suitable polyhydric alcohols are, for example, ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,3-diol, butene-1,4-diol, butyne-1,4-diol, pentane-1 , 5-diol, neopentyl glycol, bis (hydroxymethyl) cyclohexanes such as 1,4-bis (hydroxymethyl) cyclohexane, 2-methylpropane-1,3-diol, methylpentanediols, furthermore diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol , Polypropylene glycol, dibutylene glycol and polybutylene glycols into consideration. Alcohols of the general formula HO- (CH ₂ ) _x -OH, where x is a number from 1 to 20, preferably an even number from 2 to 20, are preferred. Examples of these are ethylene glycol, butane-1,4-diol, hexane-1,6-diol, octane-1,8-diol and dodecane-1,12-diol. Further preferred is neopentyl glycol.

Also included are polycarbonate diols, e.g. by reaction of phosgene with an excess of the mentioned as synthesis components for the polyester polyols low molecular weight alcohols, into consideration.

Also suitable are lactone-based polyesterdiols, which are homopolymers or copolymers of lactones, preferably terminal hydroxyl-containing addition products of lactones onto suitable difunctional starter molecules. Suitable lactones are preferably those which are derived from compounds of the general formula HO- (CH ₂ ) _z -COOH, where z is a number from 1 to 20 and an H atom of a methylene unit is also denoted by a C ₁ - to C _4- alkyl radical may be substituted. Examples are epsilon-caprolactone, beta-propiolactone, gamma-butyrolactone and / or methyl epsilon-caprolactone and mixtures thereof. Suitable starter components are, for example, the low molecular weight dihydric alcohols mentioned above as the synthesis component for the polyesterpolyols. The corresponding polymers of epsilon-caprolactone are particularly preferred. Lower polyester diols or polyether diols can also be used as starters for the preparation of the lactone polymers. Instead of the polymers of lactones, it is also possible to use the corresponding, chemically equivalent polycondensates of the hydroxycarboxylic acids corresponding to the lactones.

In addition, suitable monomers (Ia2.1) are polyether diols. They are in particular by polymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with itself, for example in the presence of BF ₃ or by addition of these compounds, optionally in admixture or in succession, to starting components with reactive hydrogen atoms, such as alcohols or amines, eg Water, ethylene glycol, propane-1,2-diol, propane-1,3-diol, 1,2-bis (4-hydroxydiphenyl) propane or aniline available. Particularly preferred is polytetrahydrofuran having a molecular weight of 240 to 5000, and especially 500 to 4500.

Also suitable are polyhydroxyolefins, preferably those having 2 terminal hydroxyl groups, for example, alpha, omega-Dihydroxypolybutadien, alpha, -omega-Dihydroxypolymethacrylester or alpha, -omega-Dihydroxypolyacrylester as monomers (Ia2.1). Such compounds are known, for example, from EP-A-0622378. Further suitable polyols are polyacetals, polysiloxanes and alkyd resins.

The polyols can also be used as mixtures in the ratio of 0.1: 1 to 1: 9.

The hardness and the modulus of elasticity of the polyurethanes can be increased if, as diols (Ia2), in addition to the diols (Ia2.1), low molecular weight diols (Ia2.2) having a molecular weight of about 62 to 500, preferably 62 to 200, g / mol , are used.

The monomers used (Ia2.2) are in particular the synthesis components of the short-chain alkanediols mentioned for the preparation of polyester polyols, the unbranched diols having 2 to 12 C atoms and an even number of C atoms and pentane-1,5-diol and neopentyl glycol are preferred.

The proportion of diols (Ia2.1), based on the total amount of diols (Ia2), is preferably 10 to 100 mol% and the proportion of monomers (Ia2.2), based on the total amount of diols (Ia2), is 0 to 90 mol%. The ratio of the diols (Ia2.1) to the monomers (Ia2.2) is particularly preferably 0.1: 1 to 5: 1, particularly preferably 0.2: 1 to 2: 1, or virtually no diols (Ia2. 2) used.

In order to achieve the water-dispersibility of the polyurethanes, the polyurethanes in addition to the components (Ia1) and (Ia2) of the (Ia1) and (Ia2) different monomers (Ia3), the at least one isocyanate group or at least one isocyanate-reactive group and In addition, at least one hydrophilic group or a group which can be converted into a hydrophilic group carry constructed. In the following text, the term "hydrophilic groups or potentially hydrophilic groups" is abbreviated to "(potentially) hydrophilic groups". The (potentially) hydrophilic groups react much more slowly with isocyanates than the functional groups of the monomers which serve to build up the polymer main chain.

The proportion of components having (potentially) hydrophilic groups in the total amount of the components (Ia1), (Ia2), (Ia3), (Ia4) and (Ia5) is generally such that the molar amount of (potentially) hydrophilic groups, based on the amount by weight of all monomers (Ia1) to (Ia5), 30 to 1000, preferably 50 to 500 and particularly preferably 80 to 300 mmol / kg.

The (potentially) hydrophilic groups may be nonionic or, preferably, (potentially) ionic hydrophilic groups.

Suitable nonionic hydrophilic groups are, in particular, poly (C ₁ -C ₄ -alkylene) glycol ethers of preferably from 5 to 100, preferably from 10 to 80, ethylene oxide repeat units. The content of polyethylene oxide units is generally 0 to 10, preferably 0 to 6 wt .-%, based on the amount by weight of all monomers (Ia1) to (Ia5).

Preferred monomers having nonionic hydrophilic groups are polyethylene oxide diols, polyethylene oxide monools and the reaction products of a polyethylene glycol and a diisocyanate which carry a terminally etherified polyethylene glycol radical. Such diisocyanates and processes for their preparation are disclosed in US Pat. Nos. 3,905,929 and 3,920,598.

Ionic hydrophilic groups are especially anionic groups such as the sulfonate, the carboxylate and the phosphate group in the form of their alkali metal or ammonium salts and cationic groups such as ammonium groups, in particular protonated tertiary amino groups or quaternary ammonium groups.

Potentially ionic hydrophilic groups are, above all, those which can be converted by simple neutralization or hydrolysis reactions into the above-mentioned ionic hydrophilic groups, e.g. Carboxylic acid groups.

(Potentially) ionic monomers (Ia3) are e.g. in Ullmann's Encyklopadie der technischen Chemie, 4th edition, volume 19, pp. 311-313 and for example in DE-A 1 495 745.

As (potentially) cationic monomers (Ia3), especially monomers having tertiary amino groups are of particular practical importance, for example: tris- (hydroxyalkyl) -amines, N, N'-bis (hydroxyalkyl) -alkylamines, N-hydroxyalkyl-dialkylamines, tris - (aminoalkyl) -amines, N, N'-bis (aminoalkyl) -alkylamines, N-aminoalkyl-dialkylamines, wherein the alkyl radicals and alkanediyl moieties of these tertiary amines independently of one another consist of 1 to 6 carbon atoms.

These tertiary amines are converted either with acids, preferably strong mineral acids such as phosphoric acid, sulfuric acid, hydrohalic acids or strong organic acids or by reaction with suitable quaternizing agents such as C ₁ - to C ₆ -alkyl halides or benzyl halides, eg bromides or chlorides in the ammonium salts.

in welcher R¹ und R² für eine C₁- bis C₄-Alkandiyl-Einheit und R³ für eine C₁- bis C₄-Alkyl-Einheit steht und vor allem Dimethylolpropionsäure (DMPA) bevorzugt.Suitable monomers with (potentially) anionic groups are usually aliphatic, cycloaliphatic, araliphatic or aromatic carboxylic acids and sulfonic acids which carry at least one alcoholic hydroxyl group or at least one primary or secondary amino group. Preference is given to dihydroxyalkylcarboxylic acids, in particular having 3 to 10 carbon atoms, as are also described in US Pat. No. 3,412,054. In particular, compounds of the general formula (Ia3.1)

in which R ¹ and R ^{2 is} a C ₁ - to C ₄ -alkanediyl unit and R ^{3 is} a C ₁ - to C ₄ -alkyl unit and especially dimethylolpropionic acid (DMPA) is preferred.

Also suitable are corresponding dihydroxysulfonic acids and dihydroxyphosphonic acids, such as 2,3-dihydroxypropanephosphonic acid.

Otherwise suitable are dihydroxyl compounds having a molecular weight above 500 to 10,000 g / mol with at least 2 carboxylate groups, which are known from DE-A 3,911,827. They are obtainable by reacting dihydroxyl compounds with tetracarboxylic dianhydrides such as pyromellitic dianhydride or cyclopentanetetracarboxylic dianhydride in a molar ratio of 2: 1 to 1.05: 1 in a polyaddition reaction. Suitable dihydroxyl compounds are, in particular, the monomers (IIa2) listed as chain extenders and also the diols (IIa1).

Suitable monomers (Ia3) with isocyanate-reactive amino groups are aminocarboxylic acids such as lysine, β-alanine or the adducts of aliphatic diprimary diamines mentioned in DE-A-2034479 to α, β-unsaturated carboxylic or sulfonic acids.

• R⁴ und R⁵ unabhängig voneinander für eine C₁- bis C₆-Alkandiyl-Einheit, bevorzugt Ethylen
  und X für COOH oder SO₃H stehen.

Such compounds obey, for example, the formula (Ia3.2)

H ₂ NR ⁴ -NH-R ⁵ -X (Ia3.2)

in the

• R ⁴ and R ⁵ independently of one another represent a C ₁ to C ₆ alkanediyl unit, preferably ethylene
  and X is COOH or SO ₃ H.

Particularly preferred compounds of the formula (IV) are N- (2-aminoethyl) -2-aminoethanecarboxylic acid and also N- (2-aminoethyl) -2-aminoethanesulfonic acid or the corresponding alkali metal salts, Na being particularly preferred as the counterion.

Further particularly preferred are the adducts of the abovementioned aliphatic diprimary diamines with 2-acrylamido-2-methylpropanesulfonic acid, as described, for example, in US Pat. in German Patent 1,954,090.

If monomers having potentially ionic groups are used, their conversion into the ionic form may take place before, during, but preferably after the isocyanate polyaddition, since the ionic monomers are often difficult to dissolve in the reaction mixture. The sulfonate or carboxylate groups are particularly preferably in the form of their salts with an alkali ion or an ammonium ion as the counterion.

In the case of using monomers (Ia3) with carboxyl groups or those groups which can be transferred to the carboxyl groups after the dispersion of the polyurethanes by hydrolysis reactions or protonation of carboxylate groups, the pH of the aqueous dispersion according to the invention is adjusted so basic that substantially no more carboxyl groups are present but these are almost completely neutralized. This is generally the case at pH >> pKs, where:
pH = pKs-log c _acid / c _salt .

Preferably, the pH is at least 8.

The monomers (Ia4) other than the monomers (Ia1) to (Ia3) are generally for crosslinking or chain extension. They are generally more than dihydric non-phenolic alcohols, amines having 2 or more primary and / or secondary amino groups and compounds which carry one or more primary and / or secondary amino groups in addition to one or more alcoholic hydroxyl groups.

Alcohols with a value higher than 2, which can serve to set a certain degree of branching or crosslinking, are, for example, trimethylolpropane, glycerol or sugar.

Also suitable are monoalcohols which, in addition to the hydroxyl group, carry a further isocyanate-reactive group, such as monoalcohols having one or more primary and / or secondary amino groups, e.g. Monoethanolamine.

Polyamines having 2 or more primary and / or secondary amino groups are used especially when the chain extension or crosslinking is to take place in the presence of water, since amines usually react faster than alcohols or water with isocyanates. This is often required when aqueous dispersions of high molecular weight crosslinked polyurethanes or polyurethanes are desired. In such cases, the procedure is to prepare prepolymers with isocyanate groups, to rapidly disperse them in water and then chain-extended or crosslinked by addition of compounds containing a plurality of isocyanate-reactive amino groups.

Amines suitable for this purpose are generally polyfunctional amines of the molecular weight range from 32 to 500 g / mol, preferably from 60 to 300 g / mol, which contain at least two amino groups selected from the group of primary and secondary amino groups. Examples of these are diamines such as diaminoethane, diaminopropanes, diaminobutanes, diaminohexanes, piperazine, 2,5-dimethylpiperazine, amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane (isophoronediamine, IPDA), 4,4'-diaminodicyclohexylmethane, 1 , 4-diaminocyclohexane, aminoethylethanolamine, hydrazine, hydrazine hydrate or triamines such as diethylenetriamine or 1,8-diamino-4-aminomethyloctane.

The amines may also be in blocked form, e.g. in the form of the corresponding ketimines (see, for example, CA-A-1 129 128), ketazines (see, for example, US-A 4,269,748) or amine salts (see US-A 4,292,226). Also oxazolidines, as used for example in US-A 4,192,937, are capped polyamines, which can be used for the preparation of the polyurethanes according to the invention for chain extension of the prepolymers. When using such capped polyamines they are generally mixed with the prepolymers in the absence of water and this mixture is then mixed with the dispersion water or a portion of the dispersion water, so that the corresponding polyamines are hydrolytically released.

Preference is given to using mixtures of di- and triamines, particularly preferably mixtures of isophoronediamine (IPDA) and diethylenetriamine (DETA).

The polyurethanes preferably contain 1 to 30, particularly preferably 4 to 25, mol%, based on the total amount of components (Ia2) and (Ia4), of a polyamine having at least 2 isocyanate-reactive amino groups as monomers (d).

Alcohols of higher valency than 2, which can serve to set a certain degree of branching or crosslinking, are e.g. Trimethylolpropane, glycerine or sugar.

For the same purpose higher than divalent isocyanates can also be used as monomers (Ia4). Commercially available compounds are, for example, the isocyanurate or the biuret of hexamethylene diisocyanate.

Monomers (Ia5), which are optionally used, are monoisocyanates, monoalcohols and monoprimary and secondary amines. In general, their proportion is at most 10 mol%, based on the total molar amount of the monomers. These monofunctional compounds usually carry further functional groups such as olefinic groups or carbonyl groups and serve to introduce functional groups into the polyurethane, which enable the dispersion or the crosslinking or further polymer-analogous reaction of the polyurethane. Suitable for this purpose are monomers such as isopropenyl-alpha, alpha-dimethylbenzyl isocyanate (TMI) and esters of acrylic or methacrylic acid such as hydroxyethyl acrylate or hydroxyethyl methacrylate.

In the field of polyurethane chemistry, it is well known how the molecular weight of the polyurethanes can be adjusted by selecting the proportions of the monomers reactive with one another and the arithmetic mean of the number of reactive functional groups per molecule.

1. A) der Molmenge an Isocyanatgruppen und
2. B) der Summe aus der Molmenge der Hydroxylgruppen und der Molmenge der funktionellen Gruppen, die mit Isocyanaten in einer Additionsreaktion reagieren können.

Normally, the components (Ia1) to (Ia5) and their respective molar amounts are chosen so that the ratio A: B with

1. A) the molar amount of isocyanate groups and
2. B) the sum of the molar amount of the hydroxyl groups and the molar amount of the functional groups which can react with isocyanates in an addition reaction.

0.5: 1 to 2: 1, preferably 0.8: 1 to 1.5: 1, more preferably 0.9: 1 to 1.2: 1. Most preferably, the ratio A: B is as close as possible to 1: 1.

The monomers used (Ia1) to (Ia5) carry on average usually 1.5 to 2.5, preferably 1.9 to 2.1, particularly preferably 2.0 isocyanate groups or functional groups which can react with isocyanates in an addition reaction ,

The polyaddition of the components (Ia1) to (Ia5) is generally carried out at reaction temperatures of 20 to 180 ° C, preferably 50 to 150 ° C under atmospheric pressure or under autogenous pressure.

The required reaction times can range from a few minutes to a few hours. It is known in the field of polyurethane chemistry how the reaction time is affected by a variety of parameters such as temperature, concentration of monomers, reactivity of the monomers.

To accelerate the reaction of the diisocyanates, the usual catalysts, such as dibutyltin dilaurate, stannous octoate or diazabicyclo (2,2,2) octane, be used.

Rührkessel come into consideration as polymerization, especially when provided by the concomitant use of solvents for a low viscosity and good heat dissipation.

Preferred solvents are immiscible with water indefinitely, have a boiling point at atmospheric pressure of 40 to 100 ° C and do not react or only slowly with the monomers.

Most often, the dispersions are prepared by one of the following methods:

According to the "acetone process", an ionic polyurethane is prepared from the components (Ia1) to (Ia3) in a solvent which is miscible with water and boils at normal pressure below 100 ° C. Add enough water to form a dispersion in which water is the coherent phase.

The "prepolymer mixing process" differs from the acetone process in that it does not produce a fully reacted (potentially) ionic polyurethane, but first a prepolymer bearing isocyanate groups. The components are chosen so that the ratio A: B is greater than 1.0 to 3, preferably 1.05 to 1.5. The prepolymer is first dispersed in water and then optionally crosslinked by reaction of the isocyanate groups with amines carrying more than 2 isocyanate-reactive amino groups, or chain-extended with amines bearing 2 isocyanate-reactive amino groups. Chain extension also occurs when no amine is added. In this case, isocyanate groups are hydrolyzed to amino groups, which react with remaining isocyanate groups of the prepolymers with chain extension.

Usually, if a solvent was used in the preparation of the polyurethane, most of the solvent is removed from the dispersion, for example by distillation at reduced pressure. The dispersions preferably have a solvent content of less than 10% by weight and are particularly preferably free from solvents.

The dispersions generally have a solids content of 10 to 75, preferably from 20 to 65 wt .-% and a viscosity of 10 to 500 m Pas (measured at a temperature of 20 ° C and a shear rate of 250 s ^-1 ).

Hydrophobic aids, which may be difficult to disperse homogeneously in the final dispersion, such as phenolic condensation resins of aldehydes and phenol or phenol derivatives or epoxy resins, and others e.g. in DE-A-3903538, 43 09 079 and 40 24 567 mentioned polymers which serve as adhesion improvers in polyurethane dispersions, for example, can be added to the polyurethane or the prepolymer before the dispersion by the methods described in the two above-mentioned writings.

According to a variant of the invention, the hydrophilic polyurethane Ibi and a carbodiimide Ibii are present in the disperse phase P.I in the form of a physical mixture.

The polyurethane Ibi may have the same structure as the polyurethane Ia with the difference that the polyurethane Ibi does not carry effective amounts of carbodiimide groups.

• Ibi1) Diisocyanaten, die frei sind von Carbodiimid-Struktureinheiten,
• Ibi2) Diolen, von denen
  • Ibi2.1) 10 bis 100 mol-%, bezogen auf die Gesamtmenge der Diole (Ibi2), ein Molekulargewicht von 500 bis 5000 aufweisen, und
  • Ibi2.2) 0 bis 90 mol-%, bezogen auf die Gesamtmenge der Diole (Ibi2), ein Molekulargewicht von 60 bis 500 g/mol aufweisen,
• Ibi3) von den Monomeren (Ibil) und (Ibi2) verschiedene Monomere mit wenigstens einer Isocyanatgruppe oder wenigstens einer gegenüber Isocyanatgruppen reaktiven Gruppe, die darüber hinaus wenigstens eine hydrophile Gruppe oder eine potentiell hydrophile Gruppe tragen, wodurch die Wasserdispergierbarkeit der Polyurethane bewirkt wird,
• Ibi4) gegebenenfalls weiteren von den Monomeren (Ibi1) bis (Ibi3) verschiedenen mehrwertigen Verbindungen mit reaktiven Gruppen, bei denen es sich um alkoholische Hydroxylgruppen, primäre oder sekundäre Aminogruppen oder Isocyanatgruppen handelt und
• Ibi5) gegebenenfalls von den Monomeren (Ibi1) bis (Ibi4) verschiedenen einwertigen Verbindungen mit einer reaktiven Gruppe, bei der es sich um eine alkoholische Hydroxylgruppe, eine primäre oder sekundäre Aminogruppe oder eine Isocyanatgruppe handelt.

Accordingly, the polyurethane Ibi is usually composed of

• Ibi1) diisocyanates which are free of carbodiimide structural units,
• Ibi2) Diols, of which
  • Ibi2.1) 10 to 100 mol%, based on the total amount of diols (Ibi2), have a molecular weight of 500 to 5000, and
  • Ibi2.2) 0 to 90 mol%, based on the total amount of diols (Ibi2), have a molecular weight of 60 to 500 g / mol,
• Ibi3) monomers other than the monomers (Ibil) and (Ibi2) having at least one isocyanate group or at least one isocyanate group-reactive group further having at least one hydrophilic group or a potentially hydrophilic group, thereby causing the water dispersibility of the polyurethanes;
• Ibi4) optionally further from the monomers (Ibi1) to (Ibi3) different polyvalent compounds having reactive groups which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups, and
• Ibi5) optionally of the monomers (Ibi1) to (Ibi4) other monovalent compounds having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.

Suitable structural components (Ibi1) are, in particular, the compounds designated as (Ia1.2), as structural components (Ib2) which come as (Ia2), as structural components (Ibi3) which come as (Ia3), as structural components (Ibi4) which are used as ( Ia4), and as constituent components (Ibi 5) the compounds designated as (Ia5).

mit

m:

einer Zahl von 2 bis 20

R^c:

wie bei der allgemeinen Formel Ia1.1.1 definiert

R^d:

― NH₂

        ―N=C=N―R^e

und R^e unabhängig von einander C₁- bis C₂₀- Alkyl, C₅- bis C₁₂-Cycloalkyl, C₆- bis C₂₀-Aryl oder C₇- bis C₂₀- Aralkyl bedeutet, wobei 1 bis 4 Wasserstoffatome der Reste R^e durch gegenüber Carbodiimidgruppen inerten Substituenten substituiert sein können.The carbodiimide Ibii carries substantially no hydrophilic groups, which cause the water dispersibility, ie it carries substantially no ionic groups or hydrophilic Polyalkylenoxidreste as they carry the monomers Ia3 and Ibi3. Suitable carbodiimides Ibii are, for example, those of the general formula IbIII

With

m:

a number from 2 to 20

R ^c :

as defined in the general formula Ia1.1.1

R ^d :

- NH ₂

-N = C = N-R ^e

and R ^e independently of one another are C ₁ - to C ₂₀ -alkyl, C ₅ - to C ₁₂ -cycloalkyl, C ₆ - to C ₂₀ -aryl or C ₇ - to C ₂₀ -aralkyl, where from 1 to 4 hydrogen atoms of the radicals R ^e may be substituted by carbodiimide inert substituents.

wobei R^a, R^b und R^d die in den Formeln Ia1.1.2 und Ibii1 angegebene Bedeutung hat und p für eine Zahl von 2 bis 20 steht

und wobei R^a und R^b die in der Formel Ia1.1.2 angegebene Bedeutung hat, p für eine Zahl von 2 bis 20 und q für eine Zahl von 1 bis 10 steht.Among these compounds, those of the general formulas Ibii2 and Ibii3 are preferred

wherein R ^a , R ^b and R ^{d have} the ^meaning given in the formulas Ia1.1.2 and Ibii1 and p is a number from 2 to 20

and wherein R ^a and R ^{b have} the meaning given in the formula Ia1.1.2, p is a number from 2 to 20 and q is a number from 1 to 10.

The carbodiimides Ibii with terminal urea or urethane groups can be prepared, for example, by reacting compounds of the formula Ia1.1.1 with the corresponding alcohols or amines.

Such compounds are known and described for example in EP-A-628 541.

The carbodiimides Ibii with terminal groups of the type -N = C = NR ^e are obtainable by condensing compounds of formula Ia1.1.1 with the corresponding monoisocyanates or by the diisocyanates from which the compounds of formula Ia1.1.1. is cocondensed together with the monoisocyanates. Preference is given to phenyl isocyanate, cyclohexyl isocyanate or m-isopropenyl-alpha-alpha-dimethylbenzyl isocyanate (TMI).

The preparation of an aqueous dispersion containing a disperse phase I in which the polyurethane Ibi and the carbodiimide Ibii are present in the form of a physical mixture can be carried out, for example, as the preparation of the polyurethanes Ia which contain a hydrophobic auxiliary. This means that the carbodiimide Ibii, if it carries no isocyanate-reactive groups such as alcoholic hydroxyl or primary and secondary amino groups, at any time of the reaction mixture from which the polyurethane Ibi is formed, can be added with the proviso that the Added admixture before the dispersion of the polyurethane Ibi in water. However, if the carbodiimide Ibii bears isocyanate-reactive groups, the addition occurs only after the reaction mixture has reacted, i. contains practically no more NCO groups.

Furthermore, it is possible to use instead of the carbodiimides Ibii, the monomers Ia1.1, provided that their addition takes place after the reaction mixture of the monomers Ibi1 to Ibi5 is reacted. In this case, the isocyanate groups of the monomers Ia1.1 react with water to give amino groups and, if appropriate, these amino groups react with further isocyanate groups of other molecules of the monomers Ia1.1 to form urea groups to form chain-extended molecules.

• II.1) 30 bis 99,98, bevorzugt 50 bis 99,8, besonders bevorzugt 80 bis 98 Gew.-% Hauptmonomere ausgewählt aus C₁- bis C₂₀-Alkyl(meth)acrylaten, Vinylestern von bis zu 20 C-Atome enthaltenden Carbonsäuren, Vinylaromaten mit bis zu 20 C-Atomen, ethylenisch ungesättigten Nitrilen, Vinylhalogeniden und aliphatischen Kohlenwasserstoffen mit 2 bis 8 C-Atomen und 1 oder 2 Doppelbindungen,
• II.2) 0,01 bis 20, bevorzugt 0,1 bis 10, besonders bevorzugt 1 bis 8 Gew.-% einer Carbonsäure mit einer olefinischen Doppelbindung und
• II.3) 0,01 bis 10, bevorzugt 0,1 bis 8, besonders bevorzugt 1 bis 5 Gew.-% eines von den Monomeren II.1 und II.2 verschiedenen Monomeren, ausgewählt aus der Gruppe bestehend aus N-Methylol(meth)acrylamid (AMOL), (MAMOL), Acetoacetoxy-ethyl-(meth)acrylat; Diaceton(meth)acrylamid; Gycidyl(meth)acrylat; Ureido-(meth)acrylat; (Meth)acrylsäureanhydrid,
• II.4) ggf. von (II.1), (II.2) und (II.3) verschiedenen radikalisch polymerisierbaren Monomeren.

As the polymer (P) contained in the disperse phase (P.II), polymers derived from

• II.1) 30 to 99.98, preferably 50 to 99.8, particularly preferably 80 to 98 wt .-% of main monomers selected from C ₁ - to C ₂₀ alkyl (meth) acrylates, vinyl esters of up to 20 C-atoms containing carboxylic acids, vinyl aromatics having up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl halides and aliphatic hydrocarbons having 2 to 8 carbon atoms and 1 or 2 double bonds,
• II.2) 0.01 to 20, preferably 0.1 to 10, particularly preferably 1 to 8 wt .-% of a carboxylic acid having an olefinic double bond and
• II.3) 0.01 to 10, preferably 0.1 to 8, particularly preferably 1 to 5 wt .-% of a monomer other than the monomers II.1 and II.2, selected from the group consisting of N-methylol ( meth) acrylamide (AMOL), (MAMOL), acetoacetoxyethyl (meth) acrylate; Diacetone (meth) acrylamide; Glycidyl (meth) acrylate; Ureido (meth) acrylate; (Meth) acrylic anhydride,
• II.4) optionally of (II.1), (II.2) and (II.3) different radically polymerizable monomers.

In connection with the polymers (IIb), (meth) acrylic is abbreviated to methacrylic or acrylic.

In order for the polymers P.II to form a disperse phase P.II, the polymers P.II generally have a solubility of less than 1 g / l at a temperature of 25 ° C. in the coherent aqueous phase of the dispersion according to the invention.

The polymers (II) are preferably composed of the following monomers.

Examples of monomers (II.1) are (meth) acrylic acid alkyl esters having a C ₁ -C ₁₀ -alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.

In particular, mixtures of (meth) acrylic acid alkyl esters are also suitable.

Vinyl esters of carboxylic acids having 1 to 20 carbon atoms are e.g. Vinyl laurate, stearate, vinyl propionate and vinyl acetate.

Suitable vinylaromatic compounds are vinyltoluene, alpha- and p-methylstyrene, alpha-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene.

Examples of nitriles are acrylonitrile and methacrylonitrile.

The vinyl halides are chloro, fluoro or bromo substituted ethylenically unsaturated compounds, preferably vinyl chloride and vinylidene chloride.

As non-aromatic hydrocarbons having 2 to 8 carbon atoms and one or two olefinic double bonds may be mentioned butadiene, isoprene, and chloroprene, and ethylene, propylene and isobutylene.

The main monomers (II.1) are also preferably used in a mixture.

Vinylaromatic compounds such as styrene, for example, often used in admixture with C ₁ -C ₂₀ alkyl (meth) acrylates, in particular with C ₁ -C ₈ alkyl (meth) acrylates, or non-aromatic hydrocarbons such as isoprene or preferably butadiene.

Suitable monomers (II.2) are preferably (meth) acrylic acid or maleic acid.

As monomers (II.4) are e.g. into account: esters of acrylic and methacrylic acid of alcohols having 1 to 20 carbon atoms, which contain at least one other heteroatom in addition to the oxygen atom in the alcohol group and / or containing an aliphatic or aromatic ring, such as 2-ethoxyethyl acrylate, 2-butoxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylic aryl, -alkaryl or cycloalkyl esters, such as cyclohexyl (meth) acrylate, phenylethyl (meth) acrylate, phenylpropyl (meth) acrylate or Acrylic acid esters of heterocyclic alcohols such as furfuryl (meth) acrylate.

In addition, monomers (II.4) are also monomers with amino or amide groups such as (meth) acrylamide, and their derivatives substituted on the nitrogen with C ₁ -C ₄ -alkyl.

Of particular importance as monomers (II.4) are hydroxy-functional monomers, for example C ₁ -C ₁₅ (meth) acrylic acid alkyl esters, which are substituted by one or two hydroxyl groups. Of particular importance as hydroxy-functional comonomers are (meth) acrylic acid C ₂ -C ₈ -hydroxyalkyl esters, such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl (meth) acrylate.

The preparation of the polymer (II) is carried out by free-radical polymerization. Suitable polymerization methods, such as bulk, solution, suspension or emulsion polymerization are known in the art.

Preferably, the copolymer is prepared by solution polymerization with subsequent dispersion in water or particularly preferably by emulsion polymerization.

The comonomers can be polymerized in the emulsion polymerization as usual in the presence of a water-soluble initiator and an emulsifier at preferably 30 to 95 ° C.

Suitable initiators are e.g. Sodium, potassium and ammonium persulfate, tert-butyl hydroperoxide, water-soluble azo compounds or redox initiators.

As emulsifiers serve e.g. Alkali salts of longer chain fatty acids, alkyl sulfates, alkyl sulfonates, alkylated aryl sulfonates or alkylated biphenyl ether sulfonates. Further suitable emulsifiers are reaction products of alkylene oxides, in particular ethylene oxide or propylene oxide, with fatty alcohols, fatty acids or phenol, or alkylphenols.

In the case of secondary aqueous dispersions, the copolymer is first prepared by solution polymerization in an organic solvent, followed by the addition of salt formers, e.g. from ammonia to carboxylic acid-containing copolymers dispersed in water without using an emulsifier or dispersing aid. The organic solvent can be distilled off. The preparation of aqueous secondary dispersions is known to the person skilled in the art and is e.g. described in DE-A-37 20 860.

Regulators can be used to adjust the molecular weight. Suitable are e.g. -SH-containing compounds such as mercaptoethanol, mercaptopropanol, thiophenol, thioglycerol, thioglycolic acid, methyl thioglycolate and tert-dodecylmercaptan, they may e.g. in amounts of 0 to 0.5 wt .-%, based on the copolymer, in addition to be used.

The type and amount of comonomers is preferably chosen so that the copolymer obtained has a glass transition temperature of -60 and + 140 ° C, preferably -60 and + 100 ° C. The glass transition temperature of the copolymer is determined by differential thermal analysis or differential scanning calorimetry according to ASTM 3418/82.

The number average molecular weight M _n is preferably from 10 ³ to 5 × 10 ⁶ , particularly preferably from 10 ⁵ to 2 × 10 ⁶ (determined by gel permeation chromatography using polystyrene as standard).

The dispersions according to the invention can be prepared particularly simply by preparing dispersions which contain the disperse phases (I) and (II) separately and then mixing them together. The mixing is uncritical and can For example, be made so that one stirs a dispersion in the other. The mixing can take place at any time before its application.

The polyurethane dispersions according to the invention may contain other water-emulsifiable or dispersible resins, such as polyurethanes, polyester, epoxy or alkyd resins, as well as commercial auxiliaries and additives such as blowing agents, defoamers, emulsifiers, thickeners and thixotropic agents, colorants such as dyes and pigments. Usually, however, the dispersions of the invention contain no effective amounts of melamine, kaolin or flame retardants.

They are suitable for example for bonding or coating of different substrates such as wood, metal, plastics, paper, leather or textile, for the impregnation of textiles and for the production of moldings and printing inks.

The processing of the polyurethane dispersions according to the invention can be carried out according to the generally customary in the adhesive, leather or paint industry, ie by spraying the dispersions on the substrate, rolls or squeegee and then dried.

In the case of processing as an adhesive, the coated workpieces are preferably joined together by pressure before drying the dispersion film or after drying with another workpiece.

Particularly strong adhesive composites are obtained by heating workpieces, which are provided with a dried adhesive film, to a temperature of approximately 50 to 100 ° C. immediately before, during or after assembly.

The adhesive compounds produced by these methods are characterized in particular by the fact that they are stable in storage and can be used to produce bonds with a high heat resistance.

Experimental part Abbreviations:

Tl =

parts

CDI =

carbodiimide

OHZ =

hydroxyl

TDI =

toluene diisocyanate

HDI =

hexamethylene diisocyanate

DBTL =

dibutyltindilaurate

DMPA =

dimethylolpropionic

RE water =

Deionized water

RT =

room temperature

In the examples, the carbodiimide of the following formula was used

OCN- (R ^C -N = C =N) _n -R ^C -NCO (Ia1.1.1)

where m means about 4 on a statistical average.

The viscosities of the dispersions were measured at a temperature of 20 ° C. and a shear rate of 250 s ^-1 using a rotary rheometer with concentric cylinders (spindle diameter 38.7 mm, cup diameter: 42.0 mm).

The particle size of the latex particles was determined indirectly by turbidity measurements. For this purpose, the turbidity of a dispersion having a solids content of 0.01 wt .-% was relative to dist. Water at a thickness of 2.5 cm and determined at room temperature. $$\mathrm{LD}=\frac{\mathrm{IntensitätDisp}\mathrm{,}\mathrm{x}100}{\mathrm{intensity\; of\; water}}$$

Determination of the K value

The K value is a measure of the molecular weight of a polymer and was determined by the method described in Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd ed., John Wiley & Sons, Inc., volume 23, p.967 is described.

A Preparation of the dispersions A1 Preparation of the starting dispersions A1.1 Preparation of Starting Dispersions of Type (I) Production Example 1:

720.8 g of a polyester of adipic acid and 1,4-butanediol (OHN = 46), 0.15 g of DBTL were reacted in 300 g of acetone with 70.6 g of HDI for 1 h at 65 ° C for 48 minutes. Then it was diluted with 700 g of acetone and cooled to 50 ° C. The NCO content was 0.6%. It was chain extended with 42.2 g of a 50% aqueous solution of the aminoethyl-aminoethanesulfonic acid Na salt and 40 g of deionized water. After 15 minutes, 30 g of an NCO-terminated polycarbodiimide of tetramethylxylylene diisocyanate with 8% NCO and 15% CDI were added and dispersed with 1200 g of demineralized water. The acetone was distilled off in vacuo at temperatures up to 43 ° C and the solids content adjusted to 40%.

Analytical values: LD: 95 Viscosity: 40 mPas K value: 71 pH: 8.7

Production Example 2:

720.8 g of a polyester of adipic acid and 1,4-butanediol (OHZ = 46), 0.15 g of DBTL were reacted in 300 g of acetone with 70.6 g of HDI for 1 h at 65 ° C for 46 min. It was then diluted with 700 g of acetone and cooled to 50 ° C. The NCO content was 0.6%. It was chain extended with 42.2 g of a 50% aqueous solution of the aminoethyl-aminoethanesulfonic acid Na salt and 40 g of deionized water. After 15 minutes, 60 g of an NCO-terminated polycarbodiimide of tetramethylxylylene diisocyanate with 8% NCO and 15% CDI were added and dispersed with 1200 g of demineralized water. The acetone was distilled off in vacuo at temperatures up to 43 ° C and the solids content adjusted to 40%.

Analytical values: LD: 89 Viscosity: 67 mPas K value: 79 pH: 8.7

Production Example 3

720.8 g of a polyester of adipic acid and 1,4-butanediol (OHZ = 46), 0.15 g of DBTL were reacted in 300 g of acetone with 70.6 g of HDI for 1 h 58 min at 65 ° C. It was then diluted with 700 g of acetone and cooled to 50 ° C. The NCO content was 0.55%. It was chain extended with 42.2 g of a 50% aqueous solution of the aminoethyl-aminoethanesulfonic acid Na salt and 40 g of deionized water. After 15 minutes, 80 g of an NCO-terminated carbodiimide of tetramethylxylylene diisocyanate with 8% NCO and 15% CDI in 80 g of acetone were added and dispersed with 1200 g of demineralized water. The acetone was distilled off in vacuo at temperatures up to 43 ° C and the solids content adjusted to 40%.

Analytical values: LD: 86 Viscosity: 36 mPas K value: 64 pH: 6.9

A2 Mixing of the dispersions

The PU dispersions from Preparation Examples 1-3 were mixed in a ratio of 7: 3 f / f with a dispersion which is structured as follows: Mix 1 to Mix 3 (according to the invention) 80% ethyl acrylate 10% methyl methacrylate 5% acrylonitrile 4% methacrylic acid 1 % N-methylol Emulsifier: Steinapol NLS
Solids content 40%;

The dispersions were also mixed with a dispersion composed as follows without N-methylolacrylamide: Mix 1v to Mix 3v (for comparison) 81% ethyl acrylate 10% methyl methacrylate 5% acrylonitrile 4% methacrylic acid Emulsifier: Steinapol NLS
Solids content 40%;

B. Performance of performance tests B.1 instantaneous peel strength at different pressing temperatures beech wood / furniture foil

Equipment: Spray gun / 1.8mm nozzle
Heatable press
timepiece
500 g weights
Circulation cabinet substrate: beech wood
PVC furniture film Roxan® N 509 type 670211 Flex
HZ mahogany Dimension: 150 x 50 mm bond area: 120 x 50 mm Assignment: Spray 70 - 90 g / m ² wet on beech wood Airing time: at least 60 minutes at RT Verklebungsweise: Hot pressing at 80 ° C
only furniture foil side press pressure: 0.5 N / mm ² pressing time: 10 s Sample storage: 3 minutes at 80 ° C immediately after lamination Test temperature: 80 ° C test load: 500 g to 3000 g Duration of test: 5 minutes per test load / up to 30 minutes peel: 180 degrees Number of samples: 5 Evaluation: Test section at the respective test load

Procedure:

On beech wood, the adhesive (without crosslinker) is applied by means of a spray gun. After drying at RT for at least 60 minutes, the furniture foil is laminated in the press onto the beech wood. Immediately after lamination and subsequent tempering (3 minutes at 80 ° C), the specimens are subjected to a heat load. It starts with 500g load. If after 5 minutes not complete peeling, the load is increased after every 5 minutes by another 500g until the furniture film is peeled off either at a distance of> 20mm or a total load of 3000 g is reached.

B.2 Static peel strength in heat "rising heat resistance" beech wood / MDF / furniture foil

Equipment: Toothed spatula (1 x 1 mm toothing)
Heatable press
timepiece
1 000 g weights
Joint temperature sensor
Circulation cabinet substrate: Beech wood / furniture film (PVC) Dimension: 150 x 50 mm bond area: 100 x 50 mm Assignment: Toothed spatula (toothing 1 x 1 mm)
on beech wood in the longitudinal direction Airing time: 60 minutes at room temperature Verklebungsweise: Hot pressing at a joint temperature of 75-79 ° C Press plate temperature above: approx. 88 ° C press pressure: 0.5 N / mm ² pressing time: 30 seconds Sample storage: 1 week at room temperature Test temperature: 50 ° C to 100 ° C - in 5 ° C steps all
30 minutes test load: 1 000 g Duration of test: 30 minutes per test temperature peel: 90 degrees Number of samples: 4 Evaluation: Operating distance at the respective
Test temperature

Procedure:

The adhesive to be tested is applied with the toothed spatula in the longitudinal direction of the beech wood. After the flash-off time of 60 minutes at room temperature, the furniture foil is laminated in the press on the coated side of the beech wood. After storage of the laminations for 1 week at room temperature, the test specimens are tested with a 1 000 g weight in a peel angle of 90 ° in a drying oven.

The test starts at 50 ° C. If no complete peeling occurred after 30 minutes, the peeled test section is marked and the temperature is raised by 5 ° C every 30 minutes.

The test is ended when the run-off distance at the respective test temperature is> 10 mm, or when reaching a temperature of 100 ° C or when the film is subjected to a very high degree of stretch. evaluation Specify the peeled test track
at the respective temperature.

B3 blocking resistance

Equipment: Spray gun / 1.8 mm nozzle
2 kg weights substrate: MDF 150 x 150 mm bond area: 120 x 50 mm Assignment: Spray 70-90 g / m ² wet on MDF Flash-off: 60 minutes at room temperature

Procedure:

On MDF, the adhesive is applied by means of a spray gun. After a drying time of 60 minutes, 5 test specimens are stacked on top of each other and, as a conclusion, a sixth is placed on top without application of glue. This stack is then loaded with 2 kg. To 24 hours is checked whether the MDF parts are glued together.

C test results

The test results are summarized in the following table example immediate resistance WSF immediately WSF after 8h open time blocking resistance Mix 1 2.8 kg 93 88 T Mix 2 3.0 kg 85 85 T Mix 3 3.0 kg 93 93 T Mix 1v 3.0 kg 83 83 K Mix 2v 3.0 kg 90 90 K Mix 3v 3.0 kg 88 85 K "V" = comparative experiment "T" = weakly separable "K" = glued

The examples and the comparative examples show that the dispersions according to the invention, in terms of immediate strength, heat resistance and open time, are comparable to those of the prior art, but have clear advantages in terms of blocking resistance.

Claims (10)

1. A latently crosslinking aqueous polyurethane dispersion, comprising

   I) a disperse phase (P.I) comprising

   Ia) a polyurethane (Ia) which, in addition to hydrophilic groups which produce water dispersibility, carries carbodiimide groups and substantially no carboxyl groups
   or

   Ib) a physical mixture of

   Ibi) a polyurethane (Ibi) which carries hydrophilic groups which produce water dispersibility and carries substantially no carbodiimide or carboxyl groups, and

   Ibii) a carbodiimide (Ibii) which carries substantially no hydrophilic groups which produce water dispersibility,

   and

   II) a disperse phase (P.II) comprising another polymer (II) which carries substantially no carbodiimide groups and is substantially derived from

   II.1) from 30 to 99.98% by weight of main monomers selected from C₁- to C₂₀-alkyl (meth)acrylates, vinyl esters of carboxylic acids comprising up to 20 carbon atoms, vinylaromatics of up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl halides and aliphatic hydrocarbons having 2 to 8 carbon atoms and 1 or 2 double bonds,

   II.2) from 0.01 to 20% by weight of a carboxylic acid having an olefinic double bond and

   II.3) from 0.01 to 10% by weight of a monomer differing from the monomers II.1 and II.2 and selected from the group consisting of N-methylol (meth)acrylamide (AMOL), (MAMOL), acetoacetoxyethyl (meth) acrylate, diacetone (meth)acrylamide, glycidyl (meth)acrylate, ureido (meth)acrylate and (meth)acrylic anhydride, and

   II.4) if appropriate, monomers differing from (II.1), (II.2) and (II.3) and capable of free radical polymerization.
2. The aqueous dispersion according to claim 1, wherein the carbodiimide groups are introduced into the polyurethane (Ia) via polyisocyanates (Ia1) of the formula Ia1.1.1
   
           OCN-(R^c-N=C=N)_n-R^c-NCO     (Ia1.1.1)
   
   where R^c is a divalent hydrocarbon radical which may have, if appropriate, urea, urethane, ester and/or ether groups, as is obtained by removing the isocyanate groups from a simple organic isocyanate or from a prepolymer having urethane groups and, if appropriate, ether or ester groups and carrying terminal isocyanate groups, where, with the presence of a plurality of radicals R^c simultaneously in the same molecule, different radicals R^c corresponding to said definition may also be present, and n is an integer or (as a statistical average) a fraction from 1 to 20, preferably from 2 to 10.
3. The aqueous dispersion according to claim 1 or 2, wherein the carbodiimide groups are introduced into the polyurethane (Ia) via polyisocyanates (Ia1) of the formula Ia1.1.2

   

   where

   R^a is a group of the formula Ia1.1.2.1

   

   R^b is a group of the formula Ia1.1.2.2

   

   and
   m is from 1 to 20.
4. The aqueous dispersion according to claims 1 to 3, wherein the phase (P.I) is substantially formed from a polyurethane (Ia) which is composed of

   Ia1) diisocyanates which

   Ia1.1) comprise carbodiimide groups and,
   if appropriate, those

   Ia1.2) which are free of carbodiimide groups,

   Ia2) diols, of which

   Ia2.1) from 10 to 100 mol %, based on the total amount of the diols (Ia2), have a molecular weight of from 500 to 5 000 and

   Ia2.2) from 0 to 90 mol %, based on the total amount of the diols (Ia2), have a molecular weight of from 60 to 500 g/mol,

   Ia3) monomers differing from the monomers (Ia1) and (Ia2) and having at least one isocyanate group or at least one group reactive toward isocyanate groups, which moreover carry at least one hydrophilic group or one potentially hydrophilic group, which produce water dispersibility of the polyurethanes,

   Ia4) if appropriate, further polyfunctional compounds differing from the monomers (Ia1) to (Ia3) and having reactive groups which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups, and

   Ia5) if appropriate, monofunctional compounds differing from the monomers (Ia1) to (Ia4) and having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.
5. The aqueous dispersion according to claims 1 to 4, wherein the polyurethane (Ibi) is composed of

   Ibi1) diisocyanates which are free of carbodiimide groups,

   Ibi2) diols, of which

   Ibi2.1) from 10 to 100 mol %, based on the total amount of the diols (Ibi2), have a molecular weight of from 500 to 5 000 and

   Ibi2.2) from 0 to 90 mol %, based on the total amount of diols (Ibi2), have a molecular weight of from 60 to 500 g/mol,

   Ibi3) monomers differing from the monomers (Ibi1) and (Ibi2) and having at least one isocyanate group or at least one group reactive toward isocyanate groups, which moreover carry at least one hydrophilic group or one potentially hydrophilic group, which produce water dispersibility of the polyurethanes,

   Ibi4) if appropriate, further polyfunctional compounds differing from the monomers (Ibi1) to (Ibi3) and having reactive groups which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups, and

   Ibi5) if appropriate, monofunctional compounds differing from the monomers (Ibi1) to (Ibi4) and having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.
6. The aqueous dispersion according to claims 1 to 4, wherein the carbodiimide Ibii is one of the formula Ibii1

   

   where

   m is from 2 to 20,

   R^c is as defined the formula Ia1.1.1

   R^d is -NH₂

   

   

   

   
   
           -N= C=N -R^e
   
   and R^e, independently of one another, are C₁- to C₂₀-alkyl, C₅- to C₁₂-cycloalkyl, C₆- to C₂₀-aryl or C₇- to C₂₀-aralkyl, it being possible for from 1 to 4 hydrogen atoms of the radicals R^e to be substituted by substituents inert to carbodiimide groups.
7. The aqueous dispersion according to claim 5, wherein the carbodiimide Ibii1 is one of the formula Ibii2

   

   where R^a, R^b and R^d have the meanings stated in the formulae Ia1.1.2 and Ibii1 and p is from 2 to 20
   or
   of the formula Ibii3

   

   where R^a and R^b have the meanings stated in the formula Ia1.1.2, p is from 2 to 20 and q is from 1 to 10.
8. The aqueous dispersion according to claims 1 to 7, wherein the phase (P.II) is substantially formed from a polymer (II) which is derived from C₁- to C₂₀-alkyl (meth)acrylates and, if appropriate, acrylonitrile as monomers (II.1) and (meth)acrylic acid as monomer (II.2).
9. The use of the dispersion according to claims 1 to 8 as an impregnating composition, coating material or adhesive.
10. An article comprising wood, metal, textile, leather or plastic, which has been adhesively bonded, impregnated or coated with an aqueous dispersion according to claims 1 to 8.